Extrusion is an old and well known process for forming plastic articles. In general, extrusion conventionally involves plasticizing solid polymer, in the form of particles, powder, etc., by heating in an extrusion machine, and building pressure in the plasticized polymer material so as to be able to force the polymer material through a forming die at a downstream, discharge end of the extrusion machine.
Heretofore, it has conventionally been the practice in extruding through dies to maintain the dimensions of the die orifice constant, and further to orient the die outlet opening, so that the extrudate—that is, the polymer material extruded from the die—is balanced along the orifice and ejected along a path that is coaxial with the path of travel of the polymer material through the extruding machine to thus produce a linear extrusion. To the extent that further forming of this linear extrudate is required, including, for instance, cross-sectional shaping and bending, such operations have been performed by subsequent processing. In these regards, U.S. Pat. No. 6,454,555, the disclosure of which is incorporated by reference herein in its entirety, is exemplary.
Thus, it would be beneficial to have an alternate means of forming extruded plastic articles having a radiused shape and variable cross-section with a minimum of downstream shaping operations on the extrudate.